1. Field of the Invention
The present invention relates to a method and a system for controlling the servicing of an aircraft which is parked at a stand at an airport, said servicing being carried out from a plurality of servicing units which are stationarily arranged adjacent to the stand. The invention further concerns a system for refuelling an aircraft.
2. Discussion of the Prior Art
As a rule, today's aircraft only stop briefly at the airport in order to set down and pick up passengers and/or to unload and load freight. During these brief stops, the aircraft has to be serviced in a number of ways. For instance, the aircraft has to be refuelled, the toilets have to be emptied and replenished with disinfectant, the batteries have to be charged, and preconditioned air and compressed air have to be supplied. Normally, the servicing of the aircraft is carried out with the aid of vehicles.
Here follows, for exemplifying purposes, a description of how the aircraft is refuelled. When the aircraft to be serviced is approaching the airport and it has been decided at which gate it is to come to a halt, i.e. at which stand the aircraft is to park, a refuelling vehicle (a so-called dispenser) is informed via the radio or a TV monitor that it is to drive out to the stand. When the aircraft has parked at the gate, the serviceman connects a hose from the vehicle to a fuel line in the ground, this fuel line being in turn connected to a fuel store. Then, he unwinds from a hose reel on the vehicle another hose which is in communication with the first hose and connects it to a refuelling point on the aircraft. At the same time, he adjusts a control valve at the refuelling point, so as to set the amount of fuel that is to be supplied to the aircraft. Information on the amount of fuel to be supplied is found on a fuel list printed out by the airline and given to the serviceman. Subsequently, the actual refuelling of the aircraft is carried out. During this operation, the serviceman is watching a mechanical counter provided in the refuelling vehicle, and he interrupts the refuelling of the aircraft when the amount of fuel indicated on the list has been supplied. If the amount of fuel set with the aid of the control valve is supplied without the serviceman interrupting the refuelling operation, the control valve will automatically turn off the fuel supply.
When the refuelling has been completed, the serviceman looks at the counter and writes down the amount of fuel supplied on the fuel list. One copy of this list is given to the captain of the aircraft so that he may sign it, and another copy is sent to the oil company, who makes use of it when invoicing the airline.
The remaining service for the aircraft is carried out in similar fashion from vehicles that are driven up to the stand. Service personnel service the aircraft according to written instructions obtained from the airline, and indicate on various forms which service has been performed and in which quantities. These forms are then given to a foreman belonging to the ground crew, who uses the information contained therein to compile a freight list which, like the fuel list, is given to the captain so that he may sign it and which also is used for invoicing purposes.
It goes without saying that it is of extreme importance that the servicing of the aircraft is correctly performed and involves the right quantities. To ensure that this is so, various control systems have been provided. For instance, the refuelling of the aircraft should, as mentioned in the foregoing, be sanctioned by the captain. There are further provided fuel meters in the aircraft, enabling a verification of the amount of fuel supplied.
Despite the provision of these control systems, errors may, however, occur. The service personnel may, for instance, mistake the amount of fuel that is to be supplied or has been supplied or write down an incorrect number on the fuel list given to the captain. An extra security risk resides in the supplementary refuelling sometimes carried out after the ordinary refuelling, for instance because the weather conditions at the emergency landing ground have worsened and one therefore has to take into account a possible landing at another emergency landing ground farther away. The information on the supplementary refuelling is often transmitted by radio or phone to the service personnel, which of course increases the risk of misunderstandings and errors.
Should a mistake, or at worst a wilful deception, occur, it is furthermore difficult to afterwards sort out what really happened, since all entries regarding the servicing carried out are based on handwritten information, which may be more or less correct. It is true that the refuelling vehicles are equipped with flow meters, but these do not indicate afterwards to which aircraft or when the recorded amount of fuel has been supplied.
It is furthermore known to carry out the servicing described above from units that are permanently arranged on the ramp. For instance, the present applicant has developed servicing units which are lowered into the ramp when not in use, but can be raised above ground with the aid of an elevator device when to be used. However, the security problems described above remain the same.